Fig. 1

Expression of B cell maturation antigen on plasma cells. The stages of B cell differentiation take place in the bone marrow and Lymphnode. When memory cells differentiate into plasma cells, BCMA expression begins and is expressed on short-lived proliferating plasmablasts, and long-lived PCs, mature B-cells and malignant B cells which are much more pronounced in malignant cells. An example is multiple myeloma cells. BCMA isn’t critical for normal B-cell homeostasis but is required for the survival of long-lived PCs. induction of BCMA expression occurs with a BAFF-R decreasing during the differentiation of PCs. APRIL and BAFF are two ligands for BCMA, And BCMA has a closely related to calcium modulator and cyclophilin ligand interactor (TACI). In addition to binding to BCMA, these ligands bind to their receptors at the cell surface, triggering signaling pathways which promote the growth and survival of PCs and activate anti-apoptotic pathways. APRIL binds to sulfated side chains of heparin sulfate proteoglycan (HSPG) its binding site to bind to TACI and BCMA. APRIL/BCMA signaling pathway Increases the activity of malignant plasma cells. BCMA is converted to soluble BCMA (sBCMA) by the enzyme protease γ-secretase, sBCMA can interfere with signaling and the level of sBCMA is a marker for b cell involvement in some disease